How to make customized forms?

  We know that we can make web forms using HTML or using Rails helpers.
I have a thought in mind. May be its has been already implemented
somewhere i don't know. Assume a quiz application. There are many
questions. Any question may have answers which must be entered in a text
box or text area or a selection drop down or radio buttons,etc. Now if
this app is meant to be social and i have users who create their quiz
have the freedom to make these fields dynamically of their own(say a
text box can have max 20 char and field is 10 char visible, name it and
these fields appear to their friends in the quiz page). Any ideas of
implementing? Thank you